1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus in which a developer image is transferred onto a sheet.
2. Description of Related Art
A known image forming apparatus comprises a transfer belt configured to convey a sheet, a photosensitive drum configured to support a developer image, and a transfer roller configured to transfer the developer image to the sheet. The photosensitive drum is disposed on one side of the transfer belt, and the transfer roller is disposed on the other side of the transfer belt so as to oppose the photosensitive drum with the transfer belt therebetween.
A dimension in a width direction of the transfer belt is set to be substantially equal to a dimension in an axial direction of the transfer roller and a dimension in an axial direction of the photosensitive drum. The transfer roller and the photosensitive drum oppose each other with the transfer belt therebetween. The transfer belt lies substantially throughout the dimensions in the axial directions of the transfer roller and the photosensitive drum.
The dimension in the width direction refers to a direction parallel to the directions in the axial directions of the transfer roller and rollers for holding the transfer belt. The dimension in the axial direction of the photosensitive drum or the transfer roller refers to a dimension in the axial direction of a portion of the photosensitive drum or the transfer roller that directly involves in image forming. Thus, the dimension in the axial direction of the photosensitive drum refers to a dimension in the axial direction of an irradiation area of the photosensitive drum. The dimension in the axial direction of the transfer roller refers to a dimension in the axial direction of a portion of the transfer roller that corresponds to the irradiation area.